1. Technical Field
The present invention relates in general to the field of telecommunications, and in particularly voice mail messages. Still more particularly, the present invention relates to a method and apparatus for receiving voice mail messages using a satellite radio coupled to a repeater, allowing voice mail messages to be received on a cellular phone when the cellular phone is out of range of a cellular base station.
2. Description of the Related Art
Cellular phones, which blend radio and telephone technology, have become ubiquitous throughout the world. As the name implies, a cellular phone is a phone that works within a “cell,” which is an area surrounding a base station transceiver that sends and receives radiotelephone traffic to the cellular phone. Each cell is of limited size, typically about 10 square miles, with the base station transceiver being in the center of the cell. By being so small, the cellular phone only has to transmit at low power (either 0.6 watts or 3.0 watts of power), which results in extended battery life.
Multiple cells are contiguous, overlapping only enough to allow a call to be handed off from one cell to another. As the user of the cellular phone moves out of a first cell into a second cell, as in when driving in a car, service to the cellular phone is passed from the tower in the first cell to the tower in the second cell, allowing the user to continue her call without a break in service.
When a user turns on her cellular phone, the cellular phone first listens for a System Identification Code (SID) on a control channel. The control channel is a special frequency channel that provides instructions to the cellular phone to set up calls, including channel protocols, handoff procedures, etc. Also set up are transmission protocols to be used, such as frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), etc.
If the cellular phone is not within a cell, that is, if the cellular phone is not within a transmission range of a base station transceiver, then the cellular phone is said to be in a “dead cell,” and no cellular telephone traffic is possible within that dead cell. When this occurs, telephone calls sent to the cellular phone, either from another cellular phone or a land-line (plain old telephone server—POTS) phone, are unable to be completed. Typically, the caller receives a message stating that the cellular phone being called is not available, due to the called cellular phone being in a dead cell, the called cellular phone already handling another call, or the called cellular phone being turned off. Whatever the reason for the call not being able to go through, a same option is offered to the caller to leave a voice mail message for the user of the called cellular phone.
A voice mail service offered by a cellular phone service provider is a combination of an answering machine and a pager. That is, the caller's voice message is recorded (“answering machine”), and the called party is then alerted (“paged”) that she has a new voice message if the cellular phone is not in a dead cell. Thus, the called party can listen to the message at a convenient future time. Typically, the called party is alerted to the presence of a new voice mail message with a data signal. That is, a typed message stating “New Voice Mail Received” will appear on a display of the cellular phone. The called party then calls her own cellular phone number, enters a personal password number, and then listens to the new voice mail.
If the called party is in a dead cell, then the voice mail service cannot contact the called party to alert her of the missed telephone call and stored voice mail message. In such a situation, then, the cellular phone service provider monitors traffic from base stations until notified that the called party is back in a “live” cell. The service provider then sends the called cellular phone the prompt alerting the user of the new voice mail message.
However, voice mail messages are often urgent, and the called cellular phone may be outside any live cell for an extended period of time. For example, consider a user of the called cellular phone who is driving through a desolate stretch of road far from civilization, where cellular coverage is spotty at best. Similarly, a user may simply be in an area for several hours or days where there is no cellular phone service. In such instances, the user cannot be notified that she has a new voice mail message.
What is needed, therefore, is a method and system that allows a cellular phone user to receive a voice mail message when outside of a live cell zone. Such a method and system would preferably utilize commonly available equipment combined with a minimal amount of hardware modification.